Method and apparatus for domestic house heating



Oct. 31, 1939. F, w Rl'EHL 2.178.268

METHOD AND APPARATUS FOR DOMESTIC HOUSE HEATING Original Filed Dc. 5, 1935 'Patented Oct. 31.. 1.939`

2.11a2ss lBIETHQ) AND APPARATUS FOB-'DOMESTIC HOUSE HEATING Frederick W. Riehl, Denver, Oolo.

` Application December 5, 1935,V serial No. 52,954 ltenewed Marchal, 1939 l s claims. (cl. 237-2) This invention relates to a method and'to an apparatus for heating domestic houses, and more 'particularly to improvements in connection with the use of automatically operated fluid fuel burning equipment.

This application is a continuation in part of application Serial N0. 667,415, filed April 22, 1933.

In the heating of the ordinary house with -steam or hot water, where an automatic 'oil or gas burner'is used; the burner is oi for relatively long periods of time and does not come on until Y the temperature in the house reaches a predetermined However, before the burner is able toheat the. -water or supply steam after it does come on, the temperature in the housefalls considerably below the desired room tempera.-

ture, and in fact, often becomes uncomfortably cold. The primary object of the present invention is therefore to provide a method of heating land ing apparatus with which the use" of radiators distributed throughout the rooms of the house, is

unnecessary. 1

Astill further object of the invention is the provision of a heat exchange unit which may be inserted-in existing hot Water and 'steam heatingl systems as well'as used in new installations, and

provides a heating system. adapted to furnish heat to rooms by using the waste heat` in ue gas and the combination of forced circulation of hot air and steam heat from. a single unit.

' Further objects'and advantages 4of the inven-A tien will be apparent from the following detailed description taken in connection with the accompanying drawing in which:

Fig'. 1 is an elevational view "of an'apparatus constructed in accordance with the .features of` the invention and adapted to' carry out the improved process.

a plan view of the apparatus lshown in Fig. 5 is an enlarged plan view of ajthermo-e.

static switch vshown in- Fig. 1.- 6v is a sectional View` of the in im. 5.

- ed form of duct.

Fig. 7 is an enlargedsectional view of one of the plurality of air heating ducts shown in Figs. 1 and 2. i

. Flg. 8 is a view similar to Fig. 7 showing a modi- "Fig. 9 is a diagrammatic view showing alternative form of control switchto be used. instead ofswitch69. p Referring to the drawing which illustrates somewhat diagrammatically a preferred form of l0 the apparatusv and certain modications, the furnace 2 comprises asteam boiler of conventionaldesign mounted on a base 4. Make up water is suppliedto theboiler through a pipe 6 provided with a valve 8. 15

The boiler 2 is heated by means of a fluid fuel burner of any desired: construction shown dla'- g'rammatically at l2.' The burner may be either an oil or gas burner, and may be supplied with preheated air through a conduit I4 which is proy, vided with a balanced valve l5 adapted to auto-y matically open when theburner fan draws air for combustion. .l

Mounted above the boiler is a heat exchange unit I G for heating air to be used for heating the g5 house and for combustion. The unitfl includes a heat exchange element comprising an L-shaped casing I8 in which is mounted a plurality of 1tubes 20 (Figs. 1, 2 and 'l and 8). Waste combustion gases from boiler 2 are 4conducted through a fur' a0 'nace outlet 22 into the lower portion of casing [8 around tubes 20, andout through a conduit 24, into a stack 26. The conduit 24 is provided with a .damper 28. 'I'he air to be heated by heat vex- 1 Achange with waste products of -combustion is induced into the unit I6, directly through the ,open end cylinder 30 `or from outside the house through extension 32 of the cylinder 30. 'The air is drawn into the unitglli by means of ta fan or blower 34 mounted therein", and forced through a Vconduit '35 into a`casing 31 then .through tubes 20. `The air conduit' 32 is controlled by a damper 36 which is operated by a thermostatic element 38 mounted` in the path of the airl passing from around theA 'tubes 20 in'r'esponse to. changes in the tempera- Vture of the air.

Mounted to the left of the fan 34 in the unit I64 :erebanks ef steam tubes 4o :adapted te further heat the air passed through the heating element comprising .the tubes 20. The tubes of bank 40 GQ may be provided with :dus and supplied-with steam from boiler 2 through-a line 42 provided Y withanair release valve 44. Condensate proswitch shown duced in banks 40 is returned' to the boiler` 'throughs line'46. The tube `4|) may be 65 constructedin any 'desired manner to provide the necessary heating surface and the tubes may be' finned.

From the heating unit I8 the air is conducted through a hot air distrbuting conduit 48 to one or more parts of the house to be heated. The hot air passed through this conduit may be humidiiied by spraying steam into the air from a distributor (not shown) which may be supplied with steam from line 42. The amount of steam introduced into the air may be controlled automatically from a humidity regulator (not shown) placed at a desired location in the house. A part of the airheated'in unit. I6 may be supplied to the burner I2 through conduit I4 which is connected into the unit I6 in advance lof the steam distributor. [Damper I5 in line I4 is adapted to admit air to the furnace only when the burner equipment.

is in operation.

Since the heating unit I6 may be used in conjunction with existing steam and hot water systems, steam may be supplied to radiators throughout the house through a line 58 and the con- 'is arranged to be operated by an electric motor 88 which may be connected in parallel with ythe burner I2 by wires 68 which connect with the wires 64 supplying current to operate the burner through lines 8i which are connected with .the burner I2, and with a\switch 88'or 18 (Fig. 9).

'.The switch 89 comprises terminals for the wires- 88, terminals for a source of electricity through wires 10 and terminals for wires 1I leading to the motor 88. As shownin Fig. 1, the

switch is thrown so that'the motor` 86 is connected in parallel with the burner i2 throughy wires 88 and 1I. Withthe switch 88 in this pomtion the thermostat A82 effects the -simultaneous starting and stopping of the burner I 2 and the motor 68, the current being supplied through the lines 85. The switch ,88 also includes a lower right pair of terminals for connecting the motor in series through lines 12, with athermostatic switch 14. When the' switch 88 is thrown so as to connect lines 18 and` 12 electricity is suppled for the motor 88 through the lines 1l. But when the switch is in this position electricity is not supplied to the motor 88 unless the thermostatic switch 14 has been closed by a temperature rise at the point. The motor 88 is operated by power from -the lines 1I under the control f the ther- -mostatic switch 14 which is closed after the burner has been started by-the thermostat 82.

'Ihe lines 1I to the motor 88 are connected respectively to the lower right terminal and through one line 12 to the switch .14. With the lswitch 88 'closed tothe right the motor 88 runs independently of the burner circuit and stops. only l after thev temperature aroundswitch 14 becomes suiliciently low to stop the current from lines 18.

One form of switch 14 suitable /for the purpose is illustrated in Figs. 5 and 6. The -switch 14 as shown includes a pair of terminals 16 which are connected to wires 12'. The wires "l2 maybe provided with plugs for inserting into the terminals 1s. The switch 1411s provided with a gimme common means for connecting terminals 1B when a certain' predetermined temperature is reached.

This includes an expansible bar or rod 18 fixed to the casing at one end and connected at the free endwith an electrical insulator 88 with a vmetal bar 82 to connect the terminals 16. The A bar 82 may always be in contact with one terminal but does not make the connection until the proper temperature is reached. The connection is broken when the temperature falls below a certain point, by contraction of the rod or bar 18. It is apparent that the motor 66 may be operated to drive the fan 84 either inhresponseito the thermostatic switch 14 (resting on the top of ilue gas casing I8 'inside the housing) which acts in response to the temperature of the flue gases from the boiler, or when the burner I2 is operated in response to the thermostat 82.

Instead of using the above arrangements for operating the motor 86 it may be started by thermostat 82 (at the same time as the burner) 'and stopped by using the mechanism shown in Fig. i) in place of switches 89. and 14. This mechanism' comprises a control box in which power lines 88' enter from the oil burner circuit and lines 1li .enter from the house circuit (as in Fig. 1).

Lines 1I from the motor 88 enter the control box and one of these lines is connected to one of the lines of 88 and of 10', the other line 1I' having two .branches which connect into opposite ends of a Mercoid valve 18. The Mercoid valve 18 connects the oil burner circuit as shownv (with mercury) when there is no heat in, or' flue gas passing through unit I8. Valve 18 is mounted upon a spring. This spring is actuated by the heat passing through unit I s (the `valve 1: and spring is preferablymounted against casing I8) and when .heated expands and automatically changes motor 68 to the house circuit =18 by tilting the Ivalve'in the opposite direction so that the mercury connects the lines 1I with the lines 18'.- Thls house circuit then furnishes fan motor 88 with electrical energy. When the spring contracts due to no more heatedair passing through.

unit I8, the valve 18 swings back `and connects circuit 88" to motor 8l. However. at this time this circuit is no longer alive as the thermostat 82 no longer calls for heat and the burner circuit is broken at that point. However, the fan will now start again on the oil burner circuit as soon as thermostat 82 calls for heat. As soon as the room thermostat registers a demand for heat in the house the burner I2 'is starts ed and -immediately gives a very hot nre in the furnace. Under ordinary conditionsa considerable time elapses before steam or hot water heat can be supplied. vThe present inventionA avoids this condition because the blower 84 starts at the same time as the burner when switches 88 or 18 are in the positions shown or as soon as flue gas heats switch 14 when switch 88 is in the opposite position. Warm air is produced immedi- Therefore there .will be rpractically no temperature drop in the ouse -below the temperature at the time when the-burner was started.

In 'the construction illustrated in Iiig. 1 with switch 88 thrown as shown. .the blower 84l will stop at the same timethe' burner is' turned oirk bythe thermostat 82. l However, air'will c'ontinuev to pass by natural convection through the tubes 28 and. around tubes 48 so that warm air' will be ately by the heat fromthe otherwise waste gases `of combustion passing around tubes 28. and supplied tothe house through hot air conduit 48.

envases coming in contact with Aelement 88 is cool, so that no cold air will'be taken from outside the las shown in Fig. 1.

.house except when the airpassing over element .'38 is warm. A

.When air is'takenfrom the outside throug inlet 32 provision is made for recirculatlng a portion of the hot alrleaving some of the tubes 20 For this purpose a duct 84 covers the outlets of about four of the tubes 2l and directs the hot air therefrom into cylinder 32.where it mixes with the 'cold air. The duct 84 is provided with a damper 81 controlled by levers from temperature 'responsive element 38 the same as damper 38; When outside air is not supplied then hot air is not forced through duct 84.

The tubes 20 for heating air are preferably provided with extra internal heat transfen'ing surface-to more effectively conduct the heat from the Aflue gas to the air inside the tubes. This may 'be done in the manner shown in Fig. 'I in which a zigzag shaped drcorrugated strip I1 of thin metal is inserted inside the tubes 20. 'I'he strip or' strips should it snugly inthe tubes. The tubes l20maybemadeintheformshowninFls28in which two similarly'bent pieces of metal I9 are welded together as at 2| to form the tubes with inside heat conducting surface.

The heat exchange element Vshown inD Figs. .3 and 4 may be used in place .of the element I8 of Fig. 1. It comprises header boxes 86 between which is mounted a plurality of finned fiue'tubes g 88.

Waste combustion gases from the boiler 'enter the lower header through inlet 22' and discharge from the upper header 88 vthrough conduit 24 into' a stack `26.

. The air to be heated Ais induced into the heat exchange unit directly through opening 90 (Fig.

' in the unit to the left of the 4blower 34'. Steam may be supplied tothe tubes 82 through a steam inlet `.94 and condensatedischarged through an outlet96. l i

A heating apparatus constructed or converted in accordance with the features` of the' present invention is adapted to provide almost instantaneous heating of a dwelling because of the heat exchange of air with waste products of combustion which usually have a.v relatively high temperature where oil or gas is used as fuel. 'I'his heat is augmentedby heat rfrom the 'radiator bank 40 which is supplied with steam after burner izstarts. The use of the eombinedapparatus of the present invention avoidsthe necessity off'radiators in the rooms of the house to be heatedv as well as the usual waste of 'space and expenses connected therewith. The heating plant is all `in the basement out of sight and out of the way,

and in a new installation supplies the necessary heatat a material saving in`- equipment cost overfurnace installations or conversion jobs now in use. The heat exchange vunit shown in' Figs'. 1 to 4 may be constructed as a'single'piece of equipment an'd installed inlnew or old heating plants excellent eiilciency is obtainedv because ferred formfwhatis claimed as ,new is:

. static means.

existing heating plants for the of vheating an added room or otherwise, the radiator bank Il and its casing may be omitted unless arelatively large amount o f additional hot air is 'desired. V'.lheuse of the radiator element Il! in 5 the heat exchange unit gives a very emcient quick acting combination because of its nearness. to the boiler.

The heat einen Vesunim shawn 1n Figs. 1

and'2 may be readily constructed from sheet 10 steel since as.I shown the various parts may be separately made and assembled. Note 'for example the lL-shaped tube heat exchange section and the motor and blower housing which fits in the L toV form a rectangular casing. The air 15 enters the tubes 28 at thetop, passes to the right,

. down and then tothe left, into the part of the casing housing the steam radiator. Note that one Z-shaped tube sheet serves -for the inlet'and L outlet of tubes 20. -20

method of heating. 'Ihe improvedprocess and apparatus of the present invention is particu- 30 larly adapted to supply.A such heat 'in a very economical manner, bothasto cost of fuel and for equipment.

It is to be understood that various modifications ofthe invention may be made without de- 35 parting from the spirit and scope thereof as de'- ned by the claims.

Having .thus described the invention in its pre' 1. A domestic house heating system for sup-1 plying an indirectdiuid heating mediumfor heatin'g the house, comprising a furnace for supplying said heating medium, means for conducting heating medium from the furnace to the houseradiators, a fluid fuel burner for delivering hot products of combustion into said furnace, thermostatic `means mounted in the house andinterconnected with-said burner for starting said J burner in response to a demand` for heat in the house and for stopping said burner,` a heat exchange unit mounted directly in the path of waste ue gases from said furnace, said unit including an element fr heating air by indirect heat exchange with waste flue gases from saig. furnace, a. propellingmeans for forcing air through said unit and an automaticallycontrolled damper for admitting fresh air to the unit when the `air vtherein is warmed by the heat exchange element, and means for' starting and stopping said propelling means when the operation of said burner isstarted and stopped by said thermo- 2. A-domestic housenhea'ting system for supplymg an indirect uuid heating medium for heatingthe house, comprising -a furnace for supplying said heating medium, means for conducting helating medium from the'furnace to the.. h`ouse radiators, ailuid fuel burneijiorsaid' frnace'controlled by a thermostat mounted in the house;

vwhereby hot products of combustion are supplied 1o to said furnace at intervals to produce said heat- `ing medium for the house radiators whenA the temperature in the house reaches a predeterv mined minimum,'a air heating unit including an air propeller and a heat exchang'ee/lement A1l of. the

. from said furnace below a predetermined mini--l adapted to heat air -by indirect heat exchange with waste flue gases, means for starting said propeller at the time said-burner is started, whereby hot air is supplied to said house for a substantial period of time before said heating medium can be supplied after the starting of said burner, and means for stopping said propeller after the stopping oi' said burner in response to a drop in temperature in the flue gases from said furnace below a predetermined minimum temperature.

3. A domestic house heating system for supply ing an indirect iiuid heating medium for heating the house, comprising a furnace for supplying said heating medium, means for conducting heat ing medium from the furnace to the house radiators, a fluid fuel burner for'delivering hot products of combustion into said furnace, thermostatic means mounted in the house and interconnected with said burner for starting said burner in response to a demand for heat in the .house andfor stopping said burner, a heaty eX- change unit mounted directly in the path of waste ilu'e' gases from said furnace, said unit inp cluding an element for heating air by indirect heat `exchange with waste flue gases from said furnace, said element comprisinga plurality of air heating tubes mounted in a casing, means for forcing air through said tubes in a path countercurrent to the flow of combustion gases therethrough, means for automatically starting said air forcingmeans at the time said burner is started, and .separate means for automatically stopping said air'forcing-.means a short time after said burner is stopped. I'

4. A domesticv house heating system as dened byclaim 3 in 'which the air forcing mea-ns is started automatically at the same time as the starting of saidburner and in which said, air

forcing, means' is stopped automatically in response to a drop in temperature of the ue gases from the furnace below a predetermined minimum temperature. f

5. A domestic house heating system as' defined by claim 2 in which `said propeller is started aumum temperature.

f 6. In the method of heating a house in whichv an indirect heating medium is supplied to house radiators from the house furnace, which in turn is interxiiittentlyV operated to burn fluid fuel therein at intervals when the temperature in the dium to the house radiators in response to a demand for heat in the house when the tempera'- ture inthe house f'allsV to a predetermined mini Imounted directly in the path of the hot waste flue gases from said furnace, said element being mum, avoiding the usual temperature drop in the house following said demand by immediately automatically-y initiating the passage of a stream of air in indirect heat exchange with hot waste combustion gases discharged from said furnace.

at the time'and by said demand to produce hot air quickly following the starting of` combustion in said furnace, conducting the resulting hot air into the part of the house desired to be heated thereby avoiding said temperature drop, and automatically discontinuing the positive 'passage of air in heat exchange with hot waste `combustion gases after the combustion of uid fuel has ceased in said furnace in response to a temperature drop in the waste combustion gases leaving said furnace.

7. In' the method of heating a house in which an vindirect heating medium is supplied to the house radiators from the house furnace, which in turn is operated at intervals by the automatic operation of a fluid fuel burner inv said furnace when the temperature in the house reaches a predetermined minimum, the improvement which comprises automatically starting-and stopping the operation of said burner according to the temperature in the house, avoiding the usual temsaid burner by substantially immediately initiating the positive passage of air in indirect heat ex change with vhot products of combustion discharged from said furnace at the same time as the starting of said burner to produce hot air quickly following the starting of said burner, forcing the resulting hot air to the part of the house desired to be heated thereby avoiding said temperature drop, automatically stopping the operation `of said burner when the temperature in the house reaches a desired predetermined point, and automatically stopping the positive passage of hot air to the house from said heat exchange after the operation of, said burner is stopped in response to a drop in temperature ofthe products of combustion from said furnace.

8.` A domestic house heating system as defined by claim 3 in which said element for heating air by indirect heat exchange with waste flue gases comprises a plurality of air heating tubes of substantially L-shape mounted in 'an L,shaped.cas

9. In the method of heating 1n which` air 1s heated ina heating unit by the intermittent op- .e'ration of a Vfluid fuel burner, the improvement which comprises starting the operation of the burner to supply heat .as required, atvthe time of starting said burner simultaneouslyl initiating the positive passage of air through vsaid unit to `be heated by hot products of combustion from said burner, stopping the operationof said burner when the required-heat has 4been supplied, and stopping the positive passage" of air to said unit after stopping the operation of said burner in response .to adrop in temperature ofthe products of combustion from saidl burner.

" FREDERICKW. RIEHL.

perature drop in the house after the starting of 'ing through which the ilue gases are conducted. i 

